It's only in development that the gadget's pagestyles.css file
isn't flipped, so if we always load via the hidden styles gadget
(which we do) it's not necessary to have any special handling
of RTL tables.

The one part that isn't clear is whether the sorting icons are
supposed to be moved, but that's an issue with tableSorter in
general; see T369592 for details.

Bug: T368367